Polymer-baking types of graphite films have excellent heat-dissipating properties, and as such, are used as heat-dissipating components for dissipating heat from components that generates heat, e.g., for semiconductor elements that are mounted in various electronic or electrical apparatuses such as computers. A conventional method for producing a graphite film has included heat-treating sheets of polymer film in batch-wise manner. However, in order to improve productivity or in order to produce a long graphite film, a method for continuously baking a polymer film that continues lengthwise has been developed. For example, Patent Literature 1 discloses a method for continuously baking a long polymer film while applying tension to the polymer film, and Patent Literature 2 discloses a method for continuously baking a long polymer film while applying as little tension as possible to the polymer film.